ddRADseq data analyses of genome-wide SNPs.

Several datasets of genome-wide SNP data inferred from Burriel-Carranza et al. (2024) [28] were used to perform population genomic, phylogenomic and species delimitation analyses. The following datasets were retrieved or assembled: i) dataset1: Dataset composed of 163 specimens from the P. rupestris species complex including all known lineages with 491 unlinked SNPs (retaining one SNP per locus) and a dataset completeness of 77% (dataset retrieved from [28], corresponding to dataset 16 in the former study); ii) dataset2: Dataset composed of the same 163 specimens produced de novo to obtain in addition invariant sites. Raw illumina reads were downloaded from Burriel-Carranza et al. (2024) [28] and processed with iPyRAD [55]. We discarded reads with ≥ 3 missing sites, consensus sequences with low coverage (<10 reads), excessive undetermined or heterozygous sites (>3), or too many haplotypes (>2). Consensus sequences were clustered across samples using the within-sample clustering threshold (89%). The resulting dataset contained 104,277 loci and 346,583 SNPs. When this dataset was used, further filtering options were applied for each analysis; iii) dataset3: Dataset composed of 173 Pristurus specimens including 10 individuals of P. flavipunctatus and 163 specimens from the P. rupestris species complex, with a total length of 137,800 bp including invariant sites (20,845 SNPs), and a dataset completeness of 70.87% (dataset retrieved from [28], corresponding to dataset 31 in the former study); iv) dataset4: Multispecies Coalescent (MSC) species tree reconstructions and species delimitation methods were implemented to a reduced dataset of 31 specimens, containing the specimens with the least missingness and with no signs of admixture from at least two representatives from each deep lineage identified by Burriel-Carranza et al. (2024) [28], and two samples from P. flavipunctatus used as outgroups. The dataset was obtained following the same procedure as in dataset2 but including a hard filtering of missing genotype call rate of 40% (i.e. all loci were present in at least 60% of the samples).

Population genomics.

Burriel-Carranza et al. (2024) [28] performed a set of several hierarchical admixture analyses to discover the most probable number of populations within the Pristurus rupestris species complex. This showed that deep lineages of the P. rupestris species complex are highly structured following the local topography of the mountain range with no signs of current admixture between the deep lineages of the Pristurus rupestris species complex (see S23, S38–S43 Figs from Burriel-Carranza et al 2024) [28]. Here, we further complement this data by implementing two other population genomic analyses. First, we performed a Principal Component Analysis (PCA) on dataset1 using Plink v2.00a2.3 [56]. Then, a fineRADstructure [57] analysis was implemented on dataset2 applying a hard filtering of missing genotype call rate of 40%. This analysis unravels different levels of structure within and between populations and its robustness to missing data is optimal for non-model organisms [57].

Genetic divergence.

We assessed the levels of intra- and interspecific genetic divergence across all lineages of the Pristurus rupestris species complex. We used dataset2 with a SNP data assembly allowing a maximum of 40% missing data at each locus, with a total of 2,712 SNPs. We clustered the samples into groups representing the 12 P. rupestris independent lineages identified in Burriel-Carranza et al. (2024) [28]. Then, we used all variant sites to calculate pairwise F_ST and d_xy across all lineage-pairs. Measures were calculated with the package PopGenome [58] implemented in R v.4.2.1 [59].

Phylogenomic reconstructions.

We used dataset3 to generate a ML phylogenomic reconstruction as a means to compare the nuclear evolutionary history of the P. rupestris species complex to the mitochondrial evolutionary history of this group (see above). The phylogenomic reconstruction was inferred through RAxML-ng v.1.0.2 [50], with a GTR+G model, a total of 100 starting trees (50 random and 50 parsimony) and 1,000 bootstrap replicates. Then, we further investigated the phylogenomic relationships within the P. rupestris species complex by generating a time-calibrated species tree inferred with SNAPP v.1.5.2 [60] under the multispecies coalescent model. We used dataset4 excluding invariant sites, keeping one biallelic SNP per locus, applying a minor allele frequency filter of 0.05, and discarding SNPs that were not present in at least 80% of the samples. We converted the resulting vcf file following Stange et al. (2018) [61] script snapp_prep.rb (available at: https://github.com/mmatschiner/snapp_prep), summarizing 2,759 SNPs. The deepest node of the phylogeny (i.e., the split between P. flavipunctatus and all representatives of the P. rupestris species complex) was constrained to be monophyletic and set to a normal distribution with a mean of 20.92 mya and σ = 1.6, following the latest calibration [28]. Samples were then assigned to their corresponding lineage (as inferred in Burriel-Carranza et al. 2024) [28] and three independent runs of 3x10⁶ generations were carried out sampling every 50 generations. Convergence between runs and stationarity was checked with Tracer v.1.7 [62]. Posterior distributions were combined with LogCombiner v.2.6.3, discarding 10% of the posterior trees as burnin and a maximum clade credibility tree was obtained calculating median heights in TreeAnnotator v.2.6.3 (both programs implemented in BEAST2 v.2.6.4; [63]).

Pristurus rupestris.

Arnold, 1977: 106 (part.); Arnold, 1986: 421 (part.); Arnold, 2009: 3 (part.); van deer Kooij, 2000: 116 (part.); Sindaco and Jeremčenko, 2008: 122 (part.); Gardner, 2013: 178 (part.); Badiane et al., 2014: 34 (part.); Šmíd et al., 2014:48; Šmíd et al., 2021: 1189; Tejero-Cicuendez et al., 2021: S1 Fig; Tejero-Cicuéndez et al., 2022: S1 Fig; Burriel-Carranza et al., 2022: 9; Burriel-Carranza et al., 2024: S1 Fig; Carranza et al., 2021: 119.

Pristurus rupestris rupestris.

Schmidt 1952: 2 (part.); Badiane et al., 2014: 33 (part.); Saberi-Pirooz et al., 2019:1; Carranza et al., 2018: S2 Appendix, 61.

Pristurus rupestris iranicus.

Schmidt 1952: 1; Wermuth 1965: 151; Badiane et al. 2014: 35.

Pristurus rupestris rupestris candidate species 1,2,3 and 4.5. Garcia-Porta et al., 2017: 5; Saberi-Pirooz et al., 2019: 11.

Pristurus rupestris rupestris Clade 4. Garcia-Porta et al., 2017: 5

Pristurus rupestris BFD1, BFD2 and BFD3. Burriel-Carranza et al., 2024: S24 Fig.

Lectotype.

The taxonomic description of Pristurus rupestris Blanford, 1874 was based on two female syntype specimens collected by W.T. Blanford in 1872 and deposited inside the same jar at the collections of the NHMUK with catalogue numbers 1874.11.23.89–90 (NHMUK:ecatalogue:1885855). The two specimens can be differentiated based on their attached labels that indicate their different origin: Muscat, Oman and Kharg island, near Bushehr, Iran. Schmidt (1952) [73] restricted the type locality of Pristurus rupestris to Muscat, Oman and described the subspecies Pristurus rupestris iranicus Schmidt, 1952 restricted to the southern coast of Iran. This included some offshore islands based on a specimen from Bushehr, Iran collected in March 10, 1937 by E.W. Kaiser and deposited at the Natural History Museum of Denmark, University of Copenhagen with catalogue number NHMD876583. More recently, Saberi-Pirooz et al. (2019) [74] analyzed specimens across the distribution range of P. r. iranicus and showed that the Iranian subspecies branched within the deep lineage composed of specimens from the type locality of P. r. rupestris (Muscat, Oman), making P. r. rupestris paraphyletic. Considering these molecular results and the lack of morphological evidence, P. r. iranicus was synonymized with P. rupestris [74]. In order to avoid any future taxonomic confusion, and based on the terra typica restricta by Schmidt (1952) [73] to Muscat, Oman, we here formally designate the specimen from Muscat, Oman from the type series deposited at the NHMUK 1874.11.23.89 as the lectotype of Pristurus rupestris.

Other material examined.

Additional specimens assigned to Pristurus rupestris sensu stricto used for morphological, genetic, genomic, and geographical analyses can be consulted in Table 1.

Diagnosis.

Pristurus rupestris corresponds to a genetically highly distinct lineage of the P. rupestris species complex. Together with Pristurus assareen sp. nov. (P. r. rupestris candidate species 16 from Garcia-Porta et al. 2017; P. rupestris BFD12 in Burriel-Carranza et al. 2024; described below) [27, 28], it constitutes the youngest divergence within the species complex with an approximate date of origin of 3.6 mya (95% HPD: 2.9–4.4 mya). Pristurus rupestris is hereafter restricted to candidate species 1,2,3 and 4.5 from Garcia-Porta et al. (2017) [27] corresponding to putative species BFD1–BFD3 from Burriel-Carranza et al. (2024) [28], and by all Iranian P. rupestris, formerly classified as P. r. iranicus but later synonymized with P. rupestris [74]. This small species of Pristurus is characterized by the combination of the following characters: (1) a maximum recorded SVL of 27.4 mm; (2) 6–7 upper labial scales; (3) 3–4 lower labial scales; (4) 3–5 small postmental scales; (5) absence of mid-dorsal enlarged scales (crest) along the body; (6) laterally compressed tail usually with conspicuous dorsal and smaller ventral enlarged scales (crest) in males, and less conspicuous (sometimes absent) in females; (7) one unique mutation in the rag2 alignment: a T instead of a C in position 276 (S1 Appendix).

Morphological, genetic and phylogeographic remarks.

Multivariate morphological analyses show that P. rupestris sensu stricto shows a broad overlap in shape morphospace with every representative of the species complex. Procrustes ANOVA and subsequent pairwise comparisons on the Principal Components of the PCA (explaining almost 50% of all shape variance; Fig 3A and S2–S4 Tables) showed significant differences between P. rupestris sensu stricto and two species described herein that only occur at mid to high elevations (P. ali sp. nov.: corresponding to P. r. rupestris candidate species 6 and 7; P. assareen sp. nov.: corresponding to P. r. rupestris candidate species 16 in Garcia-Porta et al. 2017) [27]. However, no unique diagnostic morphological characters were found between P. rupestris sensu stricto and any other Pristurus species described herein. In addition, Pristurus rupestris sensu stricto is found in sympatry and even syntopy with every species of Pristurus described in this study (S7 Table), thus identification of this species relies on molecular methods.

All mitochondrial (Fig 4A), nuclear loci (Fig 4B), and genome-wide SNP analyses (Figs 3A, 3B, 5, S1 and S2) are fully concordant in the differentiation of P. rupestris sensu stricto as a distinct species from all other species described below. In all phylogenetic reconstructions, P. rupestris sensu stricto forms a clade together with P. assareen sp. nov. (corresponding to P. r. rupestris candidate species 16 sensu Garcia-Porta et al., 2017 [27] and P. rupestris BFD12 in Burriel-Carranza et al. 2024; described below) [28] representing the youngest split within the species complex, originating about 3.6 mya (Fig 5). The results of the nuclear networks for the cmos, mc1r, rag1 and rag2 loci shown in Fig 4B, indicate that P. rupestris sensu stricto bears private alleles for some of these genes (not shared with any other species included in the present analysis). Although occurring in sympatry with all the species described herein in several localities, no signs of admixture were detected between P. rupestris sensu stricto and any other species Pristurus described below. Uncorrected p-distances with the mitochondrial 12S gene as well as F_ST estimates with genome-wide SNP data show a strong interspecific genetic differentiation (12S estimates ranging from 9–22%; F_ST values range from 0.52–0.8; S5 and S6 Tables, respectively).

Pristurus rupestris sensu stricto (Fig 8) contains high levels of intraspecific diversity (12S: 4.7%; S5 Table; F_ST values: 0.37–0.53; Fig 6). Three well-defined populations were identified in both mitochondrial and genome-wide SNP analyses. Across the southern slope of the Central Hajars we find lineage 1.2 (comprised by lineages 1 and 2 sensu Garcia-Porta et al. 2017; P. rupestris BFD1 sensu Burriel-Carranza et al. 2024) [27, 28], representing the first split within the species about 2.1 mya (95% HPD: 1.7–2.6 mya); across the northern slope of the Central Hajars and extending West until almost reaching the border with the UAE it inhabits lineage 4 (comprised by lineage 4.5 sensu Garcia-Porta et al. 2017; P. rupestris BFD3 sensu Burriel-Carranza et al. 2024) [27, 28]; finally, in the Eastern Hajars and extending West through the coastal area of the Batinah Plain lineage 3 occurs. This population is conformed by a single mitochondrial lineage, but genome-wide SNPs support the existence of two populations within this lineage, with a contact zone of admixed specimens in the western region of the Eastern Hajars (Fig 9D).

Lectotype description. As outlined above, Blanford (1874) [75] based his original description of P. rupestris on material originating from Muscat, Oman (Fig 7B.1–7B.3) as well as Kharg Island (northwest off Bushehr) in Iran (Fig 7C.1–7C.3). In his designation of the type material no information on where and which type specimens had been finally deposited was stated by the author. Although Boulenger (1885) [76] provided a thorough description of Blanford’s type material, the description of the lectotype from Muscat, Oman is still needed since he offered a general description for several syntypes only, including material from Muscat, Oman, Kharg island, Iran, and Socotra, Yemen (corresponding to Pristurus sokotranus Parker, 1938), together with measurements from a single specimen that was not identified therein [76]. After examining the available type material, we confirmed that the measurements provided by Boulenger (1885) [76] are from the female lectotype specimen from Muscat, Oman and therefore, we will use these metrics in the following description of the lectotype of Pristurus rupestris sensu stricto based on NHMUK1874.11.23.89–90 (NHMUK:ecatalogue:1885855), an adult female specimen with attached locality tag referring to Muscat, Oman. Specimen ventrally damaged with internal tissue apparent in the abdomen near the pelvic girdle and with dorsal skin partially wrinkled; tail missing. Body length 23 mm, head length 9 mm, and head width 5.5 mm. Moderately built, round body; limbs slender. Head robust and does not rise very steeply in profile, snout slightly blunt. Supranasals are separated into two scales. Scales on snout granular, polygonal and slightly pointed upwards. Scales on snout, anterior to eyes, are larger than those on top of head. Palpebral fold edged anteriorly with large scales and with pointed (ciliate) scales. Ear opening ellipsoidal. Upper labials (right/left) 6/6. Lower labials (right/left) 4/4, the fourth decreasing in size from the three large anterior scales. Four enlarged scales running backwards along the proximal borders of the third lower labials to end at about the level of the angle of the mouth. Mental large, wedge-shaped, truncated posteriorly by three postmental scales. Gulars small, rather pointed posteriorly, becoming slightly imbricate and bigger in size on throat. Dorsal scales on body small, polygonal and homogeneous, slightly pointed posteriorly. Ventrals flat and distinctly imbricate. Limbs slender. Scales on dorsal and anterior surface of the forelimbs slightly larger than dorsal body scales, flat and imbricate, fairly pointed. Scales beneath the upper forelimbs granular and smaller than ventral body scales; those beneath lower forelimbs large, flat, imbricate, and polygonal, larger than ventral body scales. Claws relatively shallow and weakly recurved. Scales on dorsal and anterior surface of hindlimbs large, flat and imbricate, fairly pointed. Scales beneath the upper hindlimbs granular and smaller than ventral body scales, those beneath lower hindlimbs large, flat, imbricate and polygonal, larger than ventral body scales.

Coloration in alcohol is grayish brown dorsally; faint thin dorsal midline pale grayish. Dorsally and both left and right of the midline irregularly-shaped whitish blotches present. Head presents the same color as the body with a broad dark brownish stripe running from the nostril through the eye and then dorsolaterally until above the ear opening. Faint large dark blotches are located from the gular region to the insertion of the hindlimbs ventrally, decreasing in number and brightness posteriorly. Ventral background coloration is grayish-whitish. Limbs banded dorsally with dark gray, light gray bands reaching until toes. Ventral coloration of limbs is grayish, darker than the abdomen and not banded.

Distribution.

In the Arabian Peninsula, P. rupestris sensu stricto is now restricted to the Omani Hajar Mountains, spanning from Ra’s al Hadd to 40 km North of the Wadi Jizzi gap (almost reaching the UAE border; Fig 9). It has been recorded from sea level up to 2,115 m asl in Jabal Shams, Central Hajars, Oman. Some specimens from lineage 3 (candidate species 3 in Garcia-Porta et al. 2017; P. rupestris BFD2 in Burriel-Carranza et al., 2024) [27, 28] and lineage 4 (candidate species 4.5 in Garcia-Porta et al. 2017; P. rupestris BFD3 in Burriel-Carranza et al., 2024) [27, 28] have been recently discovered in Masirah Island and most probably are the result of human introduction (work in progress). The designation of morphologically typical P. rupestris sensu lato introduced populations from Qatar, Bahrain, eastern Saudi Arabia and the northern UAE coast, from Sharjah to Abu Dhabi and offshore islands, will need to be genetically reassessed in the light of the here presented taxonomic revision to corroborate their identity. Since it was shown that the Iranian P. rupestris genetically fall within a clade of specimens close to the type locality in Oman [74], they are here considered as P. rupestris sensu stricto. Therefore, outside the Arabian Peninsula, P. rupestris sensu stricto is found throughout the coast of Iran, reaching North to Bushehr, in Kharg island, and spreading south until almost reaching Pakistan [77, 78]. Pristurus rupestris sensu stricto has been reported marginally from southwestern coastal Pakistan adjacent to the Iranian border [19], but its presence in Pakistan is considered uncertain by Kamali (2020) [78], and it is not included in a recent checklist provided for Pakistani reptiles by Khan (2016) [77].

Habits.

They are usually found on rocks, boulders, tree trunks, and human-made structures. Females lay single hard-shelled eggs throughout the year. They are mainly diurnal (although they can be active after sunset) and perform complex signaling including curling their tail up over the back, push-ups and inflating and laterally compressing their body and throat.

Conservation.

Pristurus rupestris sensu stricto should be listed as Least Concern in view of its large distribution within Oman, its abundance, and because it is unlikely to be declining fast enough to qualify for listing in a threatened category.

Pristurus rupestris.

Arnold, 1977: 106 (part.); Arnold, 1986: 421 (part.); Arnold, 2009: 3 (part.); van deer Kooij, 2000: 116 (part.); Sindaco and Jeremčenko, 2008: 122 (part.); Gardner, 2013: 178 (part.); Badiane et al., 2014: 34 (part.).

Pristurus rupestris rupestris candidate species 8 and 9. Garcia-Porta et al., 2017: 5.

Pristurus rupestris rupestris Clade 1. Garcia-Porta et al., 2017: 5; Saberi-Pirooz et al., 2019:11.

Pristurus sp5. Šmíd et al., 2021: 1189; Tejero-Cicuendez et al., 2021: S1 Fig; Tejero-Cicuéndez et al., 2022: S1 Fig; Burriel-Carranza et al., 2022: 9; Burriel-Carranza et al., 2024: S1 Fig; Carranza et al., 2018: S2 Appendix, 66; Carranza et al., 2021: 119.

Pristurus rupestris SP8 and SP9. Saberi-Pirooz et al., 2019:11.

Pristurus rupestris BFD5 and BFD6. Burriel-Carranza et al., 2024: S24 Fig.

Holotype.

ZFMK 104096 (sample code S8000), adult male from Tiwi, 12 m asl, Eastern Hajars (North Oman), 22.84441’N, 59.24189’E, WGS84, collected in November 2010 by J. Garcia-Porta (assigned to Pristurus rupestris rupestris candidate species 8 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD5 from Burriel-Carranza et al. 2024; see Table 1).

Paratypes.

NHMOK 2657 (sample code S7541), adult male from Sumayyan road, 1,005 m asl, Eastern Hajars (North Oman), 22.83326’N, 58.98821’E, WGS84, collected in May 2011 by S. Carranza, F. Amat and E. Gómez-Díaz (assigned to P. r. rupestris candidate species 9 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD5 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; MZB 2024–0988 (sample code S9012; MorphoBank M849884–M849886), adult male from Fulayj, 132 m asl, Eastern Hajars (North Oman), 22.42828’N, 59.35618’E, WGS84, collected in May 2011 by S. Carranza, F. Amat and E. Gómez-Díaz (assigned to P. r. rupestris candidate species 9 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD5 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; IBES7508 (sample code S7508; MorphoBank M849878–M849882), adult male from Tiwi, 28 m asl, Eastern Hajars (North Oman), 22.8448’N, 59.24156’E, WGS84, collected in May 2011 by S. Carranza, F. Amat and E. Gómez-Díaz (assigned to P. r. rupestris candidate species 8 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD5 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; IBES7276 (sample code S7276; MorphoBank M849893–M849896), adult male from Fulayj, 212 m asl, Eastern Hajars (North Oman), 22.33769’N, 59.31128’E, WGS84, collected in May 2011 by S. Carranza, F. Amat and E. Gómez-Díaz (assigned to P. r. rupestris candidate species 9 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD5 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; MZB 2024–0987 (sample code S7737; MorphoBank M849864–M849867), adult female from Ashila, 42 m asl, Eastern Hajars (North Oman), 21.95181’N, 59.6082’E, WGS84, collected in October 2010 by S. Carranza and F. Amat (assigned to P. r. rupestris candidate species 9 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD5 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; IBES7708 (sample code S7708; MorphoBank M849869–M849871), adult female from Al Ashkharah, 13 m asl, Eastern Hajars (North Oman), 21.84242’N, 59.56673’E, WGS84, collected in October 2010 by S. Carranza and F. Amat (assigned P. r. rupestris candidate species 9 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD5 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; IBECN4297 (sample code CN4297; MorphoBank M849873–M849876), adult female near Wadi Naam, 457 m asl, Eastern Hajars (North Oman), 22.70851’N, 58.77569’E, WGS84, collected in May 2013 by S. Carranza, F. Amat, M. Metallinou, M. Simó-Riudalbas and P. de Pous (assigned to P. r. rupestris candidate species 9 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD5 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; IBES9013 (sample code S9013; MorphoBank M849888–M849891), adult female from Wadd, 136 m asl, Eastern Hajars (North Oman), 22.53899’N, 59.36823’E, WGS84, collected in May 2011 by S. Carranza, F. Amat and E. Gómez-Díaz (assigned to P. r. rupestris candidate species 9 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD5 from Burriel-Carranza et al. 2024; see Table 1) [27, 28].

Other material examined.

Additional Pristurus omanensis sp. nov. specimens formerly assigned to P. r. rupestris candidate species 8 and 9 from Garcia-Porta et al. (2017) [27] and Pristurus rupestris BFD5 and BFD6 from Burriel-Carranza et al. (2024) [28] used for morphological, genetic, genomic, and geographical analyses are found in Table 1.

Etymology.

The species epithet ‘omanensis’ is an adjective that refers to the distribution range of the species, restricted to the Omani side of the Al Hajar Mountain range.

Diagnosis.

Pristurus omanensis sp. nov. corresponds to a genetically highly distinct lineage of the Pristurus rupestris species complex sensu Garcia-Porta et al. (2017) [27] from the Central and Eastern Hajar Mountains (North Oman). It represents the oldest split within the Pristurus rupestris species complex, having diverged from all other species within the group around 10.8 mya (95% HPD: 8.7–12.6 mya; Fig 5). This small species of Pristurus is characterized by the combination of the following characters: (1) a maximum recorded SVL of 25.8 mm; (2) 6–8 upper labial scales; (3) 4–5 lower labial scales; (4) 3–5 small postmental scales; (5) absence of mid-dorsal enlarged scales (crest) on the body; (6) laterally compressed tail usually with conspicuous dorsal and smaller ventral enlarged scales (crest) in males, and less conspicuous (sometimes absent) in females; (7) four unique mutations in the mc1r alignment: A instead of G in position 45; T instead of C in position 438; A instead of G in position 443; T instead of G in position 510; (8) one unique mutation in the cmos alignment: A instead of G in position 260; (9) two unique mutations in the rag1 alignment: T instead of C in position 205; G instead of A in position 242; (10) four unique mutations in the rag2 alignment: A instead of G in position 17; G instead of A in position 61; G instead of A in position 67; A instead of C in position 348 (see S1 Appendix).

Morphological, genetic and phylogeographic remarks.

Multivariate morphological analyses show that P. omanensis sp. nov. presents some degree of morphospace overlap with every representative from the species complex (Fig 3A). However, while it is not significantly distinct from P. rupestris sensu stricto and a Pristurus feulneri sp. nov. (corresponding to Clade 3 in Garcia-Porta et al., 2017 and described below) [27], it is significantly distinct from the other two species that only occur at mid to high elevations (P. ali sp. nov. and P. assareen sp. nov. which correspond to Clade 2 and candidate species 16 in Garcia-Porta et al. 2017; S2–S4 Tables, respectively; species described below) [27]. Pristurus omanensis sp. nov. is monophyletic in both mitochondrial and nuclear phylogenies (Figs 4A, 5 and S1). According to the analysis of divergence time estimation inferred with dataset4, this species diverged from all other relatives within the Pristurus rupestris species complex about 10.3 mya (95% HPD: 8.7–12.41 mya; Fig 5). The results of the nuclear networks shown in Fig 4B indicate that all alleles of P. omanensis sp. nov. for all independent loci analyzed (mc1r, cmos, rag1 and rag2) are private (not shared with any other species included in the present study). Pristurus omanensis sp. nov. is the species with the greatest genetic differentiation within the Pristurus rupestris species complex, with 21–24.5% interspecific distance in the mitochondrial 12S gene (S5 Table) and a genome-wide fixation index above 0.8 with all other Pristurus species (Fig 6). Moreover, while Pristurus rupestris sensu stricto and the other species described herein are usually found throughout the entire elevation gradient (or from mid to high elevations), P. omanensis sp. nov. seems to be restricted to low elevations, rarely exceeding 1,000 m asl (only one record from a total of 102 records; Table 1). Even though Pristurus omanensis sp. nov. is found in sympatry at less than 100 m with Pristurus rupestris sensu stricto and with another Pristurus species described below (S7 Table), no evidence of gene flow has been found between these species (Fig 3B and 3C; Burriel-Carranza et al. 2023: S38 Fig) [28].

Pristurus omanensis sp. nov. (Fig 12) presents some intraspecific diversity with 2.9% of genetic distance in the mitochondrial gene 12S (S5 Table) and an F_ST value of 0.25 between the populations that comprise this species (Fig 6). Phylogenetic (Fig 4A), phylogenomic (Figs 5 and S1) and population genomic analyses (Fig 3B and 3C) support the presence of two independent parapatric lineages within P. omanenis sp. nov.. However, mitochondrial and genome-wide nuclear SNPs disagree in the topology and composition of such lineages. Mitochondrial data recover an isolated clade, restricted to the northeasternmost distribution of P. omanensis sp. nov. (referred to Pristurus rupestris rupestris candidate species 8 in Garcia-Porta et al. 2017) [27], while the other lineage is comprised by specimens from both the Eastern and Central Hajars (referred to Pristurus rupestris rupestris candidate species 9 in Garcia-Porta et al. 2017; Figs 4A and 13C) [27]. On the other hand, genome-wide nuclear data recover all specimens from the Eastern Hajars as a unique evolutionary unit, sister to the specimens inhabiting the Central Hajars, with a hybrid contact zone with admixed specimens where both populations overlap in distribution (referred to P. rupestris putative species BFD5 and BFD6 in Burriel-Carranza et al. 2024, Figs 3C, 13D and S1) [28]. Such mito-nuclear discordance between specimens inhabiting the Central and Eastern Hajars is not uncommon in geckos (see Burriel-Carranza et al. 2023c for a similar example in Trachydactylus hajarensis) [40], and since the mitochondrial genome is maternally inherited, it could be representative of dispersal differences between males and females. Given that gene flow exists, that admixed specimens are observed in nature and, together with the lack of support for species status in the MSC species delimitation approach implemented by means of BPP and gdi (Figs 5 and S1), we believe that the two lineages within P. omanensis sp. nov. reflect intraspecific diversity and should be considered as distinct populations of the same species.

Description of the holotype.

ZFMK 104096 (sample code S8000) (Fig 10). Adult male. Complete specimen, with the tail detached. Data on nine morphometric and two pholidotic variables (see Materials and Methods) are provided in S1 Table. SVL 22.2 mm, head length 28.8% of SVL, and head width 59% of head length. Moderately built, round body, habitus comparable to P. rupestris sensu stricto; limbs and tail not especially slender. Head robust and does not rise very steeply in profile, snout slightly blunt. Nostril separated from the rostral and situated between three scales: a wide supranasal extending to the midline margin, a small upper postnasal and a large lower postnasal extending laterally along the lower edge. Supranasals are separated into two scales. Scales on snout granular, polygonal and slightly pointed upwards. About nine scales in a straight line from the lower postnasal to the anterior edge of the orbit. Scales on snout, anterior to eyes, are larger than those on top of head. Around 24 scales across mid-orbital region. Palpebral fold edged anteriorly with large scales and not edged with pointed (ciliate) scales. Ear opening ellipsoidal. Upper labials (right/left) 7/7. Lower labials (right/left) 4/4, the fourth decreasing in size from the three large anterior scales. Four enlarged scales running backwards along the proximal border of the third lower labial to end at about the level of the angle of the mouth. Mental large, wedge-shaped, truncated posteriorly by five gular scales. Gulars small, rather pointed posteriorly, becoming slightly imbricate on throat. Dorsal scales on body small, polygonal and homogeneous, slightly pointed posteriorly. Ventrals flat and distinctly imbricate. Scales on dorsal and anterior surface of the forelimbs slightly larger than dorsal body scales, flat and imbricate, fairly pointed. Scales beneath the upper forelimbs granular and smaller than ventral body scales; those beneath lower forelimbs large, flat, imbricate and polygonal, larger than ventral body scales. Claws relatively shallow and weakly recurved. Scales on dorsal and anterior surface of hindlimbs large, flat and imbricate, fairly pointed. Scales beneath the upper hindlimbs granular and smaller than ventral body scales, those beneath lower hindlimbs large, flat, imbricate and polygonal, larger than ventral body scales. Regenerated tail relatively short and robust, anteriorly more or less cylindrical, posteriorly slightly compressed. Ridges of strongly elongated scales present, low crest on midline and on lower midline of tail is made up of a longitudinal row of enlarged scales, more enlarged dorsally. Tail scales large, flat and imbricate, pointed posteriorly; dorsals and ventrals considerably larger than those on the body.

Coloration in alcohol is grayish brown dorsally; broad dorsal midline pale grayish. Dorsally and both left and right of the midline irregularly shaped reddish blotches present. Dorsolaterally thin discontinuous pale reddish lines that dissolve into irregularly distributed spots on the flanks. Whitish spots are distributed in transversal rows laterally, and double the diameter of the reddish lines. Head is the same color as the body with a broad dark brownish stripe running from the nostril through the eye and then dorsolaterally until above the ear opening. Single large dark blotches are located from beneath the eye to the entire gular region reaching posteriorly to the insertion of the forelimbs. Larger and more prominent blotches are distributed laterally on the throat decreasing in brightness ventrally. Ventral background coloration is creamish-whitish. Limbs pale beige dorsally, toes not banded. Tail similarly colored like dorsals, with pale reddish spots scattered.

The figured μ-CT-scanned specimen (Fig 10B) has a maximal skull length of 6.7 mm, maximal height of 3.2 mm and maximal width of 4.0 mm. 25 presacral vertebrae. Noteworthy minor qualitative cranial osteological differences (Fig 10C) to the other holotype specimens of the Pristurus rupestris species complex are: Vomer posteriorly rounded and bordered by a heart-shaped opening; osseous naris edge sharp and almost right angled; premaxilla and nasal steep to frontal region.

Variation.

Data on nine morphometric and two pholidotic variables (see Materials and Methods) for all eight paratypes (see above) are provided in S1 Table. Largest male 25.4 mm SVL; largest female 22.6 mm SVL. All paratypes have broken or incomplete tails; four of eight have the throat sliced, three of eight individuals show damaged skin. Paratype NHMOK 2657 (sample code S7541) has a regenerated tail. Dorsal coloration ranges from pale beige to dark gray, with thin or absent pale grayish dorsal midlines. Dorsal pattern consisting of incomplete thin reddish lines to reddish blotches, bordered by similar-sized pale whitish spots. Laterally small reddish spots present in all paratypes, in some individuals also present ventrolaterally. Few to multiple large gular blotches present in all paratypes (Fig 11).

Distribution.

Pristurus omanensis sp. nov. is endemic to Oman. It is only found at low elevations surrounding the southern areas of the Central Hajars, and surrounding the southeastern region of the Eastern Hajars up until Ras al Hadd and then entering North until Qurayyat, Oman. Despite several extensive surveys, it has never been found in the Western Hajars or in the northern slopes of the Central Hajars. It has been recorded from 0 m asl up to 1,005 m asl, although it is rarely found above 700 m asl (only one record out of 102).

Habits.

P. omanensis sp. nov. is a diurnal species, although it can also be seen active after sunset. It is abundant on rocks, boulders, tree trunks, and human-made structures such as walls, houses, and gardens. It performs complex signaling including push-ups, inflating and laterally compressing the body and throat, and curling and waving the tail up over the back. It preys on ants and other arthropods using a sit-and-wait strategy. Females lay single hard-shelled eggs throughout the year.

Conservation.

This species is endemic to the Hajar Mountain range in Oman. Whilst the area of occupancy (AOO) is restricted, the species should be assessed as Least Concern in view of its presumed large and stable population, occurrence in more than ten locations, and absence of continuing decline in AOO, extent of occurrence (EOO), or in habitat area or quality and extent.

Pristurus rupestris.

Arnold, 1977: 106 (part.); Arnold, 1986: 421 (part.); Arnold, 2009: 3 (part.); van deer Kooij, 2000: 116 (part.); Sindaco and Jeremčenko, 2008: 122 (part.); Gardner, 2013: 178 (part.).

Pristurus rupestris rupestris candidate species 6 and 7. Garcia-Porta et al., 2017: 5.

Pristurus r. rupestris Clade 2. Garcia-Porta et al., 2017: 5; Saberi-Pirooz et al., 2019:11.

Pristurus sp2. Šmíd et al., 2021: 1189; Tejero-Cicuendez et al., 2021: S1 Fig; Tejero-Cicuéndez et al., 2022: S1 Fig; Burriel-Carranza et al., 2022: 9; Burriel-Carranza et al., 2024: S1 Fig; Carranza et al., 2018: S2 Appendix, 63; Carranza et al., 2021: 119.

Pristurus rupestris SP6 and SP7. Saberi-Pirooz et al., 2019: 11.

Pristurus rupestris BFD4. Burriel-Carranza et al., 2024: S24 Fig

Holotype.

ZFMK 104093 (sample code S7547), adult male from Sayma road, 1,327 m asl, Eastern Hajars (North Oman), 22.76619’N, 59.03366’E, WGS84, collected in May 2011 by S. Carranza, F. Amat and E. Gómez-Díaz (assigned to Pristurus rupestris rupestris candidate species 7 from Garcia-Porta et al. 2017; Pristurus rupestris BFD4 from Burriel-Carranza et al. 2024; see Table 1) [27, 28].

Paratypes.

IBES7509 (sample code S7509; MorphoBank M849691–M849693), adult male from Tiwi road, 1,717 m, Eastern Hajars (North Oman), 22.82554’N, 59.08568’E, WGS84, collected in May 2011 by S. Carranza, F. Amat and E. Gómez-Díaz (assigned to Pristurus rupestris rupestris candidate species 7 from Garcia-Porta et al. 2017; Pristurus rupestris BFD4 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; IBECN4240 (sample code CN4240; MorphoBank M849687–M849689), adult male from Al Salil, 1,691 m, Eastern Hajars (North Oman), 22.83206’N, 59.02031’E WGS84, collected in May 2013 by S. Carranza, F. Amat, M. Metallinou, P. de Pous and Marc Simó-Riudalbas (assigned to Pristurus rupestris rupestris candidate species 7 from Garcia-Porta et al. 2017; Pristurus rupestris BFD4 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; IBES7193 (sample code S7193; MorphoBank M849682–M849685), adult male from Tiwi road, 1,533 m, Eastern Hajars (North Oman), 22.82532’N, 59.11173’E, WGS84, collected in December 2010 by J. Garcia-Porta (assigned to Pristurus rupestris rupestris candidate species 7 by Garcia-Porta et al. 2017; Pristurus rupestris BFD4 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; NHMOK 2653 (sample code S7226), adult male from Jabal Bani Jabir, 1,956 m, Eastern Hajars (North Oman), 22.71105’N, 59.14123’E, WGS84, collected in December 2010 by J. Garcia-Porta (assigned to Pristurus rupestris rupestris candidate species 7 from Garcia-Porta et al. 2017; Pristurus rupestris BFD4 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; IBES7539 (sample code S7539; MorphoBank M849700–M849703), adult female from Jabal Bani Jabir, 2,045 m, Eastern Hajars (North Oman), 22.70583’N, 59.1421’E, WGS84, collected in May 2011 by S. Carranza, F. Amat and E. Gómez-Díaz (assigned to Pristurus rupestris rupestris candidate species 7 from Garcia-Porta et al. 2017; Pristurus rupestris BFD4 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; MZB 2024–0983 (sample code S7225; MorphoBank M849705–M849708), adult female from Tiwi road, 1,533 m, Eastern Hajars (North Oman), 22.82532’N, 59.11173’E, WGS84, collected in December 2010 by J. Garcia-Porta (assigned to Pristurus rupestris rupestris candidate species 7 from Garcia-Porta et al. 2017; Pristurus rupestris BFD4 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; MZB 2024–0984 (sample code S7563; MorphoBank M849695–M849698), adult female from Tiwi road, 1,559 m, Eastern Hajars (North Oman), 22.84148’N, 59.09768’E, WGS84, collected in May 2011 by S. Carranza, F. Amat and E. Gómez-Díaz (assigned to Pristurus rupestris rupestris candidate species 7 from Garcia-Porta et al. 2017; Pristurus rupestris BFD4 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; IBECN8286 (sample code CN8286; MorphoBank M849715–M849719), adult female from Tiwi road, 2,046 m, Eastern Hajars (North Oman), 22.71016’N, 59.14027’E, WGS84, collected in November 2014 by S. Carranza (assigned to Pristurus rupestris rupestris candidate species 7 from Garcia-Porta et al. 2017; Pristurus rupestris BFD4 from Burriel-Carranza et al. 2024; see Table 1) [27, 28]; IBES7211 (sample code S7211; MorphoBank M849710–M849713), adult female from Jabal Bani Jabir, 1,956 m, Eastern Hajars (North Oman), 22.71105’N, 59.14123’E, WGS84, collected in December 2010 by J. Garcia-Porta (assigned to Pristurus rupestris rupestris candidate species 7 by Garcia-Porta et al. 2017; Pristurus rupestris BFD4 from Burriel-Carranza et al. 2024; see Table 1) [27, 28].

Other material examined.

Additional Pristurus ali sp. nov. specimens previously assigned to P. r. rupestris candidate species 7 (same as type specimens) and 6 from Garcia-Porta et al. (2017) [27], and to P. rupestris BFD4 from Burriel-Carranza et al. (2024) [28] that were used for morphological, genetic, genomic, and geographical analyses can be consulted in Table 1.

Etymology.

The species epithet ‘ali’ is dedicated to Ali Alghafri from the Environment Authority, Oman in recognition for his companionship, guidance and help during several field expeditions across the Hajar Mountains of Oman dedicated to the study of the geckos of the Pristurus rupestris species complex, among other reptiles. The species epithet name is defined as a noun in apposition (not a noun in the genitive case) to avoid ending with a non-euphonious double-i.

Diagnosis.

Pristurus ali sp. nov. corresponds to a genetically highly distinct lineage from the Pristurus rupestris species complex sensu Garcia-Porta et al. (2017) [27] inhabiting the Eastern Hajar Mountains (North Oman). It represents the second oldest split within the Pristurus rupestris species complex, having diverged from all the other species within the group (except Pristurus omanensis sp. nov. which represents the oldest split) around 6.9 mya (95% HPD: 5.6–8.2 mya; Fig 5), and is restricted to a somewhat small geographic range (Fig 17). This small species of Pristurus is characterized by a combination of the following characters: (1) a maximum recorded SVL of 25.8 mm; (2) 6–7 upper labial scales; (3) 4 lower labial scales; (4) 3–6 small postmental scales; (5) absence of mid-dorsal enlarged scales (crest) on the body; (6) laterally compressed tail usually with conspicuous dorsal and smaller ventral enlarged scales (crest) in males, and less conspicuous (sometimes absent) in females; (7) five unique mutations in the mc1r alignment: C instead of T in position 147; G instead of A in position 286; C instead of T in position 399; G instead of A in position 531; C instead of T in position 648; (8) five unique mutations in the cmos alignment: C instead of T in position. 6; G instead of A in position 98; A instead of C in position 147; C instead of T in position 153; A instead of G in position 225; (9) 1 unique mutation in the rag1 alignment: A instead of G in position 206; (10) 1 unique mutation in the rag2 alignment: G instead of T in position 405 (see S1 Appendix).

Morphological, genetic and phylogeographic remarks.

Morphological differentiation of Pristurus ali sp. nov. from other species of the Pristurus rupestris species complex is convoluted, and even though there are no unique diagnostic characters to distinguish these species, P. ali sp. nov. specimens tentatively have a more robust body, specifically shorter brachia and wider scapular girdles, than Pristurus rupestris sensu stricto, P. omanensis sp. nov. and P. feulneri sp. nov. (which is described below and corresponds to P. r. rupestris candidate species 10.11,12–15 in Garcia-Porta et al. 2017; Pristurus rupestris BFD7–BFD11 in Burriel-Carranza et al. 2024) [27, 28] as evidenced by the morphological multivariate analyses (Fig 3A and S2–S4 Tables). The reconstructed morphospace of the P. rupestris species complex represented by the first two Principal Components of the PCA (explaining almost 50% of all shape variance; Fig 3A), revealed some differentiation of Pristurus ali sp. nov., yet the range of variation of this species still overlapped with the other taxa. Procrustes ANOVA and subsequent pairwise comparisons generally corroborated these findings, where differences among candidate species were found between P. ali sp. nov. and all other taxa with the exception of the below described P. assareen sp. nov. (P. r. rupestris candidate species 16 in Garcia-Porta et al. 2017; Pristurus rupestris BFD12 in Burriel-Carranza et al. 2024) [27, 28]. Specifically, differences between these candidate species were due to distinct head dimensions, shorter brachium length and wider scapular and pelvic girdles in P. ali sp. nov., as evidenced by PC loadings and procrustes ANOVAs on the individual variables (S2–S4 Tables). These findings are in agreement with Garcia-Porta et al. (2017) [27] and would correspond to the robust morphotype described therein. Comparisons of within species variance found no differences among putative taxa, which was likewise observed in the overlapping distributions in the PCA. Taken together, although our morphological analyses found some evidence that while Pristurus ali sp. nov. was somewhat distinct morphologically, there were no diagnostic morphological traits that distinguished the species unambiguously and could be used as a morphological taxonomic character for this group. Pristurus ali sp. nov. is also geographically separated from P. omanensis sp. nov. by its elevational occurrence across its distribution range. While both species can be found in the Eastern Hajars, the former has been only found above 900 m asl while the latter is mostly found below 700 m asl.

Molecular analyses show a strong differentiation between P. ali sp. nov. and all other species of the P. rupestris species complex. The results of the nuclear networks for the cmos, mc1r and rag2 loci shown in Fig 4B, indicate that P. ali sp. nov. has private alleles for each of these genes (not shared with any other species included in the present analysis). Pristurus ali sp. nov. is monophyletic in both mitochondrial (Fig 4A) and nuclear (Figs 5 and S1) phylogenetic analyses. This species diverged from its sister group (all other species in the Pristurus rupestris species complex except for P. omanensis sp. nov.) about 6.8 mya, representing the second oldest divergence event within the species complex (Fig 5). Uncorrected p-distances for the mitochondrial 12S gene (9.4–21.1%; S5 Table) as well as population genomic fixation indexes (F_ST > 0.65 in all pairwise comparisons; S6 Table) support a great deal of differentiation between P. ali sp. nov. and the other Pristurus species. Furthermore, no signs of gene flow are apparent between P. ali sp. nov. even though it has been recorded in sympatry with P. rupestris sensu stricto and the below described P. feulneri sp. nov. (P. r. rupestris candidate species 15 in Garcia-Porta et al. 2017; P. rupestris BFD11 in Burriel-Carranza et al. 2024; S7 Table) [27, 28]. Similar to P. omanensis sp. nov., mitochondrial and nuclear phylogenies yielded contrasting results when interrogating the intraspecific diversity within P. ali sp. nov. The mitochondrial phylogenetic reconstruction recovered two distinct allopatric lineages within P. ali sp. nov. (corresponding to P. r. rupestris candidate species 6 and 7 from Garcia-Porta et al. 2017) [27]. However, when using genome-wide nuclear SNP data, this segregation disappeared in the phylogenomic reconstructions as well as in population structure analyses, and P. ali sp. nov. was recovered as a single, homogeneous population (corresponding to Pristurus rupestris BFD4 in Burriel-Carranza et al. 2024) [28]. When the mitochondrial separation is enforced, the genome-wide F_ST value inferred with dataset2 is as low as 0.06 (Fig 6).

Description of the holotype.

ZFMK 104093 (sample code S7547) (Fig 14). Adult male. Complete specimen with the tip of the tongue missing (used for DNA extraction), throat damaged and tail detached in two separate parts. Data on nine morphometric and two pholidotic variables (see Materials and Methods) are provided in S1 Table. SVL 23.8 mm, head length 30.4% of SVL, and head width 63% of head length, tail tip regenerated. Moderately built, round body, habitus comparable to P. rupestris sensu stricto; limbs and tail not especially slender. Head robust and does not rise very steeply in profile, snout slightly blunt. Nostril separated from the rostral and situated between three scales: a wide supranasal extending to the midline margin, a small upper postnasal and a large lower postnasal extending laterally along the lower edge. Supranasals separated in two scales. Scales on snout granular, polygonal and slightly pointed upwards. About nine scales in a straight line from the lower postnasal to the anterior edge of the orbit. Scales on snout, anterior to eyes, larger than those on top of head. Around 21 scales across mid-orbital region. Palpebral fold edged anteriorly with large scales and not edged with pointed (ciliate) scales. Ear opening round. Upper labials (right/left) 7/7. Lower labials (right/left) 4/4, the fourth decreasing in size from the three large anterior scales. Four enlarged scales running backwards along the proximal borders of the third lower labials to end at about the level of the angle of the mouth. Mental large, wedge-shaped, truncated posteriorly by four gular scales. Gulars small, rather pointed posteriorly, becoming slightly imbricate on throat. Dorsal scales on body small, polygonal and homogeneous, slightly pointed posteriorly and granular. Ventrals flat and distinctly imbricate. Scales on dorsal and anterior surface of the forelimbs large, flat and imbricate, fairly pointed. Scales beneath the upper forelimbs granular and smaller than ventral body scales; those beneath lower forelimbs large, flat, imbricate and polygonal, larger than ventral body scales. Claws relatively shallow and weakly recurved. Scales on dorsal and anterior surface of hindlimbs large, flat and imbricate, fairly pointed. Scales beneath the upper hindlimbs granular and smaller than ventral body scales, those beneath lower hindlimbs large, flat, imbricate and polygonal, larger than ventral body scales. Tail relatively short and robust, anteriorly more or less cylindrical, posteriorly slightly compressed, with a slight groove along each side. Ridges of strongly elongated scales present, low crest on midline and on lower mid-line of tail is made up of a longitudinal row of enlarged scales, more enlarged dorsally. Tail scales large, flat and imbricate, pointed posteriorly; dorsals and ventrals considerably larger than those on body.

Coloration in alcohol is light brown above; broad but blurred dorsal midline pale and slightly grayish. Dorsolaterally discontinuous thin pale reddish lines that dissolve into rows of small spots ventrolaterally to the flanks. Pale whitish spots distributed in an irregular pattern dorsolaterally, and roughly double the diameter of the reddish spots. Head light brown with a broad dark brownish stripe running from close to the nostril through the eye and then dorsolaterally until above the ear opening. Single large dark spots located right beneath the angle of the mouth until the third lower labial scale. Same-colored but roughly half the diameter sized spots conformed by two to three gular scales present on the ventral side of the throat, distributed from the level of the anterior eye opening to the insertion of the forelimbs. Ventral coloration whitish. Limbs light brown with irregular dark brown markings above, ventrally pale, toes not banded. Tail similarly colored like dorsals, pale gray-brown above with blurred, light, narrow cross-bars in the non-regenerated part.

The figured μ-CT-scanned specimen (Fig 14B) has a maximal skull length of 7.8 mm, maximal height of 3.4 mm and maximal width of 4.5 mm. 26 presacral vertebrae. Noteworthy minor qualitative cranial osteological differences (Fig 14C) to the other holotype specimens of the Pristurus rupestris species complex are: Quadratum well-developed and slightly laterally protruding; ossified cranium; sclerotic rings strongly ossified; vomer posteriorly rounded and bordered by a heart-shaped opening; osseous naris edge smooth and slightly rounded; premaxilla and nasal rising moderately steep to frontal region.

Variation.

Data on nine morphometric and two pholidotic variables (see Materials and methods) for all nine paratypes (see above) are provided in S1 Table. Largest male 25.7 mm SVL; largest female 24.3 mm. Eight of nine paratypes have completely or partially broken tails; three of nine have the throat sliced. Paratype IBECN4240 (sample CN4240) has a partially regenerated tail. Dorsal coloration ranging from pale beige to grayish, with only blurred and thin pale to orangish dorsal midlines present in some individuals usually in females. Multiple small dark brownish gular spots present in all paratypes, ranging from a blend to prominent appearance. Ventrally inconspicuous dark brownish to reddish small spots present in some paratypes, but ventrolaterally only and not reaching to midventral region (Fig 15).

Distribution.

Pristurus ali sp. nov. is endemic to Oman, where it has only been found in the Eastern Hajars (Fig 17). Despite intensive surveys across the Hajar Mountain range, it has never been found to the West of the Eastern Hajars. It is only found in mid to high elevations as it has only been recorded from 919 m asl up to 2,046 m asl.

Habits.

Pristurus ali sp. nov. is a diurnal species, although it can also be seen active after sunset. It has been found on rocks, boulders and tree trunks but most probably it is also present inside the mountain villages on human-made structures such as walls, houses, and gardens (Fig 16). It performs complex signaling including push-ups, inflating and laterally compressing the body and throat, and curling and waving the tail up over the back. It preys on ants and other arthropods using a sit-and-wait strategy. Females lay single hard-shelled eggs throughout the year.

Conservation.

This species is endemic to a restricted area of the Eastern Hajar Mountains in Oman. It has an area of occupancy (AOO) of 76 km² and an extent of occurrence (EOO) of 307 km². Despite the restricted EOO and AOO, there are no known threats and no continuing decline in habitat area or quality, and the species should be assessed as Least Concern in view of its distribution, abundance, and presumed large and stable population.

Pristurus rupestris.

Arnold, 1977: 106 (part.); Arnold, 1986: 421 (part.); Arnold, 2009: 3 (part.); van deer Kooij, 2000: 116 (part.); Sindaco and Jeremčenko, 2008: 122 (part.); Gardner, 2013: 178 (part.).

Pristurus rupestris rupestris candidate species 10.11, 12, 13, 14 and 15. Garcia-Porta et al., 2017: 5.

Pristurus r. rupestris Clade 3. Garcia-Porta et al., 2017: 5; Saberi-Pirooz et al., 2019:11.

Pristurus sp3. Šmíd et al., 2021: 1189; Tejero-Cicuendez et al., 2021: S1 Fig; Tejero-Cicuéndez et al., 2022: S1 Fig; Burriel-Carranza et al., 2019: S1 Appendix: 35; Burriel-Carranza et al., 2022: 9; Burriel-Carranza et al., 2024: S1 Fig; Carranza et al., 2018: S2 Appendix, 64; Carranza et al., 2021: 119).

Pristurus rupestris SP10/11, SP12, SP13, SP14 and SP15. Saberi-Pirooz et al., 2019: 11.

Pristurus rupestris BFD7, BFD8, BFD9, BFD10 and BFD11. Burriel-Carranza et al., 2024: S24 Fig.

Holotype.

ZFMK 104094 (sample code S6102), adult male from Lizq, 482 m, Eastern Hajars (North Oman), 22.71765’N, 58.15035’E, WGS84, collected in November 2010 by J. Garcia-Porta (assigned genetically to Pristurus rupestris rupestris candidate species 13 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD9 from Burriel-Carranza et al. 2024; see Table 1) [27, 28].

Paratypes.

IBECN3699 (sample code CN3699; adult male; MorphoBank M849798–M849800), MZB 2024–0986 (sample code CN7939; adult male; MorphoBank M849785–M849787), IBECN7239 (sample code CN7239; adult male; MorphoBank M849778–M849783), MZB 2024–0985 (sample code CN7213; adult female; MorphoBank M849789–M849791) four specimens from Mizbar, 549 m, Eastern Hajars (North Oman), 23.14319’N, 58.42435’E, WGS84, collected in November 2014 by S. Carranza (assigned to Pristurus rupestris rupestris candidate species 13 from Garcia-Porta et al. 2017; Pristurus rupestris BFD9 in Burriel-Carranza et al. 2024; see Table 1) [27, 28]; IBES7533 (sample code S7533; MorphoBank M849793–M849796), adult male; NHMOK 2655 (sample code S7551), adult female; two specimens from Mizbar, 555 m, Eastern Hajars (North Oman), 23.14307’N, 58.4244’E, WGS84, collected in May 2011 by S. Carranza, F. Amat and E. Gómez-Díaz (assigned to Pristurus rupestris rupestris candidate species 13 from Garcia-Porta et al. 2017; Pristurus rupestris BFD9 in Burriel-Carranza et al. 2024; see Table 1) [27, 28].

Other material examined.

Additional Pristurus feulneri sp. nov. specimens formerly assigned to P. r. rupestris candidate species 10.11, 12, 13, 14 and 15 from Garcia-Porta et al. (2017) [27] and to Pristurus rupestris BFD7–BFD11 in Burriel-Carranza et al. (2024) [28] that were used for morphological, genetic, genomic, and geographical analyses can be consulted in Table 1.

Etymology.

The species epithet “feulneri” is a genitive Latin noun in honor of American Naturalist Gary R. Feulner, Chairman of the Dubai Natural History Group since 1995, in recognition for his 39 years of dedication and contributions to advancing our understanding of the biodiversity and biogeography of the fauna and flora of the Hajar Mountains.

Diagnosis.

Pristurus feulneri sp. nov. corresponds to a genetically highly distinct lineage from the diverse Pristurus rupestris species complex inhabiting the Hajar Mountains (North Oman and Eastern UAE). This species represents the most abundant Pristurus species of the Hajar Mountains and is distributed across the whole mountain range (Fig 21). Pristurus feulneri sp. nov. is characterized by a combination of the following characters: (1) a maximum recorded SVL of 27.3 mm; (2) 6–7 upper labial scales; (3) 4–5 lower labial scales; (4) 3–6 small postmental scales; (5) absence of mid-dorsal enlarged scales (crest) on the body; (6) laterally compressed tail usually with conspicuous dorsal and smaller ventral enlarged scales (crest) in males, and less conspicuous (sometimes absent) in females; (7) one unique mutation in alignment cmos: an A instead of a G in position 241; (8) two unique mutations in alignment rag1: T instead of C in position 94; A instead of G in position 206 (see S1 Appendix).

Morphological, genetic and phylogeographic remarks.

Pristurus feulneri sp. nov. is morphologically cryptic from the other species of the Pristurus rupestris species complex.

The reconstructed morphospace of the P. rupestris species complex (Fig 3A) revealed that P. feulneri’s sp. nov. morphospace completely overlaps with P. rupestris sensu stricto and P. omanensis sp. nov., and presents a great deal of overlap with P. ali sp. nov. and P. assareen sp. nov. (Pristurus rupestris candidate species 16 in Garcia-Porta et al. 2017; Pristurus rupestris BFD12 in Burriel-Carranza et al. 2024; described below) [27, 28]. Procrustes ANOVA and subsequent pairwise comparisons (S3 and S4 Tables) corroborated that there were no significant differences between P. feulneri sp. nov. and the first two species while there were significant differences with the last two. Specifically, differences between these candidate species were due to distinct head dimensions, longer brachium length, and narrower scapular and pelvic girdles in P. feulneri sp. nov.. These findings are in agreement with Garcia-Porta et al. (2017) [27] and could correspond to the slender morphotype described therein. Tentatively, P. feulneri sp. nov. seems to present a more apparent dorsal midline in both males and females (especially in specimens from the Western and Central Hajars; Figs 19 and S5–S8), than P. rupestris sensu stricto (Fig 7), P. omanensis sp. nov. (Figs 11, 12 and S3), P. ali sp. nov. (Figs 14, 15 and S4), and P. assareen sp. nov. (Pristurus rupestris rupestris candidate species 16. Garcia-Porta et al. 2017; Pristurus rupestris BFD12. Burriel-Carranza et al., 2024; Figs 21 and 22; described below) [27, 28]. Pristurus feulneri sp. nov. occurs syntopically with P. rupestris sensu stricto, P. omanensis sp. nov. and P. ali sp. nov. (S7 Table).

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Fig 22. External and internal morphology of Pristurus assareen sp. nov. holotype specimen ZFMK104095 (sample code CN3704).

(A) Ventral, lateral and dorsal external view of the specimen; (B) Ventral, lateral and dorsal internal view obtained through μ-CT scanning; (C) close up of head bone structures of the P. assareen sp. nov. holotype specimen.

https://doi.org/10.1371/journal.pone.0315000.g022

Molecular analyses on mitochondrial (Fig 4A), nuclear loci (Fig 4B), and genome-wide SNP data (Figs 3B, 3C, 5, 6, S1 and S2) are fully concordant with the differentiation of P. feulneri as a distinct species from the other representatives of the Pristurus rupestris species complex. Pristurus feulneri is monophyletic in both mitochondrial (Fig 3A) and nuclear phylogenetic analyses (Figs 5 and S1). In all phylogenetic reconstructions, it forms a clade together with P. rupestris sensu stricto and the fourth species of Pristurus described below (Pristurus rupestris rupestris candidate species 16. Garcia-Porta et al. 2017; Pristurus rupestris BFD12. Burriel-Carranza et al., 2024) [27, 28], which split apart about 4.5 mya (95% HPD: 3.6–5.3 mya; Fig 5). The results of the nuclear networks for the mc1r, cmos, rag1 and rag2 loci shown in Fig 4B, indicate that P. feulneri sp. nov. has some private alleles for each of these genes (not shared with any other species included in the present analysis), especially in cmos where all haplotypes are private. Uncorrected p-distances with the mitochondrial 12S marker (13.5–24.5%; S5 Table) as well as F_ST estimates (0.61–0.83; S6 Table) with genome-wide SNP data show a strong interspecific genetic differentiation.

Pristurus feulneri sp. nov. is the species of the Pristurus rupestris species complex with the highest intraspecific diversity (uncorrected p-distance of the mitochondrial 12S gene = 8.4%; S5 Table). Phylogenetic reconstructions with the mitochondrial marker 12S recovered similar results to the ones observed in Garcia-Porta et al. (2017) [27]. However, with the inclusion of new specimens not present in the former study, we were able to identify another deep lineage within Pristurus feulneri sp. nov. from the Central Hajars, to which we assigned the lineage number 17 (Fig 4A). Intraspecific genome-wide F_ST values inferred with dataset2 ranged from 0.38–0.69 between populations, showing a great deal of differentiation within this species (Fig 6). Moreover, species delimitation analysis inferred through BPP A10 support the existence of up to four species within P. feulneri sp. nov. (Fig 5) but the gdi approach suggest that this diversity is not fully supported as interspecific diversity with the exception of candidate species 15 in Garcia-Porta et al. (2017) (P. rupestris BFD 11 in Burriel-Carranza et al., 2024; Figs 5 and S2) [27, 28]. However, topological discordances in the internal nodes of P. feulneri sp. nov. were found between mitochondrial phylogenetic reconstructions (Fig 3A), phylogenomic reconstructions (S1 Fig), and MSC species tree reconstructions (Fig 5), which could suggest incomplete lineage sorting. Also, although levels of genetic divergence between candidate species 15 in Garcia-Porta et al. (2017) (P. rupestris BFD 12 in Burriel-Carranza et al., 2024) [27, 28] and the other populations within P. feulneri sp. nov. are high, the former seems to fall within the cluster of intraspecific divergence rather than interspecific estimates (Fig 6). Therefore, we refrain from further splitting any allopatric populations of P. feulneri sp. nov. until more data are available. In the Eastern Hajars we find the deepest lineage within the species, which diverged from all other P. feulneri sp. nov. about 2.9 mya (95% HPD: 2.3–3.4 mya; formerly assigned to P. rupestris candidate species 15 in Garcia-Porta et al. 2017; P. rupestris BFD11 in Burriel-Carranza et al. 2024; Fig 5) [27, 28]. This clade is sister to all other deep lineages of P. feulneri sp. nov. in the genome-wide SNP analyses (Figs 5 and S1) but conforms a monophyletic clade with lineage 17 in the mitochondrial phylogenetic reconstruction (Fig 4A). Also in the Eastern Hajars but further west, we find the population assigned to P. rupestris rupestris candidate species 13 in Garcia-Porta et al. (2017) [27] and to P. rupestris BFD9 in Burriel-Carranza et al. (2024) [28]. The greatest diversity of P. feulneri sp. nov. populations is found in the Central Hajars with one population inhabiting the Semail gap (P. rupestris rupestris candidate species 12 in Garcia-Porta et al. 2017; P. rupestris BFD8 in Burriel-Carranza et al. 2024) [27, 28], another population inhabiting the southern slope of the Jabal Akhdar (conformed by lineage 17 and P. rupestris rupestris candidate species 14 in Garcia-Porta et al 2017; Pristurus rupestris BFD10 in Burriel-Carranza et al. 2024) [27, 28], and a third population in the northern slope of the Jabal Akhdar (P. rupestris rupestris candidate species 10.11 in Garcia-Porta et al. 2017; P. rupestris BFD7 in Burriel-Carranza et al. 2024; Fig 21C and 21D) [27, 28], which extends to the West until the Musandam Peninsula and to all the coastal and island localities across the western UAE (see Distribution below). Therefore, Pristurus feulneri sp. nov. is the only species of the Pristurus rupestris species complex present in the UAE.

Description of the holotype.

ZFMK 104094 (sample code S6102) (Fig 18). Adult male. Specimen ventrally sliced from gular fold to insertion of hindlimbs (internal tissue used for DNA extraction), right lower forelimb with ventral incision and tail missing (only the first 2 mm of the anterior part present). Data on nine morphometric and two pholidotic variables (see Materials and Methods) are provided in S1 Table. SVL 24.6 mm, head length 27.5% of SVL, and head width 63% of head length. Moderately built, round body, habitus comparable to P. rupestris; limbs and tail not especially slender. Head robust and does not rise very steeply in profile, snout slightly blunt. Nostril separated from the rostral and situated between three scales: a wide supranasal extending to the midline margin, a small upper postnasal and a large lower postnasal extending laterally along the lower edge. Supranasals are separated in two scales. Scales on snout granular, polygonal and slightly pointed upwards. About nine scales in a straight line from the lower postnasal to the anterior edge of the orbit. Scales on snout, anterior to eyes, are larger than those on top of head. Around 26 scales across mid-orbital region. Palpebral fold edged anteriorly with large scales and not edged with pointed (ciliate) scales. Ear opening droplet-shaped. Upper labials (right/left) 7/7. Lower labials (right/left) 4/4, the fourth decreasing in size from the three large anterior scales. Five enlarged scales running backwards along the proximal borders of the third lower labials to end at about the level of the angle of the mouth. Mental large, wedge-shaped, truncated posteriorly by four small postmental scales. Gulars small, rather pointed posteriorly, becoming slightly imbricate on throat. Dorsal scales on body small, polygonal and homogeneous, slightly pointed posteriorly. Ventrals flat and distinctly imbricate. Scales on dorsal and anterior surface of the forelimbs slightly larger than dorsal body scales, flat and imbricate, fairly pointed. Scales beneath the upper forelimbs granular and smaller than ventral body scales; those beneath lower forelimbs large, flat, imbricate and polygonal, larger than ventral body scales. Claws relatively shallow and weakly recurved. Scales on dorsal and anterior surface of hindlimbs large, flat and imbricate, fairly pointed. Scales beneath the upper hindlimbs granular and smaller than ventral body scales, those beneath lower hindlimbs large, flat, imbricate and polygonal, larger than ventral body scales. Tail rudiment cylindrical, bearing the first anterior scales of the caudal crest on midline made up of a longitudinal row of enlarged scales.

Coloration in alcohol grayish brown dorsally; broad dorsal midline pale grayish. Dorsolaterally thin pale reddish lines that dissolve into discontinuous lines posteriorly, and also ventrolaterally to the flanks. Bright whitish spots distributed in transversal rows dorsolaterally, and more than double the diameter of the reddish lines. Head same color as the body with irregularly distributed bright whitish spots. A broad dark brownish stripe running from the nostril through the eye and then dorsolaterally until above the ear opening, bordered both dorsally and ventrally by blurred pale grayish bands. Single large dark blotches located from beneath the angle of the mouth to the entire gular and ventral region reaching posteriorly to the insertion of the hindlimbs. Most of them being conformed by more than four gular scales, with larger and more prominent blotches on the throat decreasing in size posteriorly. Ventral background coloration is creamish-whitish. Limbs dark pale ventrally and brownish with bright whitish spots dorsally, forming regular bright whitish bands dorsally on the toes. Tail rudiment similarly colored like dorsals.

The figured μ-CT-scanned specimen (Fig 18B) has a maximal skull length of 7.1 mm, maximal height of 2.8 mm and maximal width of 4.1 mm. 25 presacral vertebrae. Noteworthy minor qualitative cranial osteological differences (Fig 18C) to the other holotype specimens of the Pristurus rupestris species complex are: Quadratum not laterally protruding; parabasisphenoid damaged; vomer posteriorly only slightly rounded and bordered by a hoof-shaped opening; osseous naris edge smooth and slightly rounded; parietal incompletely ossified; premaxilla and nasal moderately steep to frontal region.

Variation.

Data on nine morphometric and two pholidotic variables (see Materials and Methods) for all six paratypes (see above) are provided in S1 Table. Largest male 25.3 mm SVL; largest female 24.4 mm. All paratypes have broken or incomplete tails; two of six have the throat sliced. Paratype IBECN7239 (sample CN7239) has a regenerated tail. Dorsal coloration similar for all paratypes, with conspicuous broad dorsal midline colored pale grayish to bright orange-beige. Dorsal bright spots present in all paratypes, colored pale-beige to yellowish. Multiple large gular blotches present in all paratypes. Ventral pattern variable, but dark brownish to reddish spots present in all paratypes, being distributed from ventrolaterally only to covering the entire ventral region (Fig 19).

Distribution.

This species of Pristurus is the most ubiquitous of its genus in the Hajar Mountains and the only species of the Pristurus rupestris species complex present in the UAE. It has been recorded throughout the whole mountain range, from the Musandam Peninsula in the Western Hajars to Ras al Hadd in the Eastern Hajars. It is distributed throughout the UAE and Oman and it has been recorded from sea level up to 2,317 m asl in the Jabal Kawr (Central Hajars, Oman). There are records of introduced populations along the western UAE coast and surrounding islands (Fig 21A), most likely due to the transport of rocks and sediments from the Hajar Mountains for the development of coastline infrastructures.

Habits.

Pristurus feulneri sp. nov. is a diurnal species, although it can also be seen active after sunset. It is abundant on rocks, boulders, tree trunks, and human-made structures such as walls, houses, and gardens (Fig 20). It performs complex signaling including push-ups, inflating and laterally compressing the body and throat, and curling and waving the tail up over the back. It preys on ants and other arthropods using a sit-and-wait strategy. Females lay single hard-shelled eggs throughout the year.

Conservation.

Pristurus feulneri sp. nov. should be considered as Least Concern in view of its distribution, abundance, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a threatened category.

Pristurus rupestris.

Arnold, 1977: 106 (part.); Arnold, 1986: 421 (part.); Arnold, 2009: 3 (part.); van deer Kooij, 2000: 116 (part.); Sindaco and Jeremčenko, 2008: 122 (part.); Gardner, 2013: 178 (part.).

Pristurus rupestris rupestris candidate species 16. Garcia-Porta et al., 2017: 5.

Pristurus sp4. Šmíd et al., 2021: 1189; Tejero-Cicuendez et al., 2021: S1 Fig; Tejero-Cicuéndez et al., 2022: S1 Fig; Burriel-Carranza et al., 2022: 9; Burriel-Carranza et al., 2024: S1 Fig; Carranza et al., 2018: S2 Appendix, 65; Carranza et al., 2021: 119.

Pristurus rupestris SP16. Saberi-Pirooz et al., 2019: 11.

Pristurus rupestris BFD12. Burriel-Carranza et al., 2024: S24 Fig.

Holotype.

ZFMK 104095 (sample code CN3704), adult male from Wadi As Sareen Nature Reserve, 1,682 m asl, Eastern Hajars (North Oman), 22.13182’N, 58.61912’E, WGS84, collected in November 2014 by S. Carranza (assigned to Pristurus rupestris rupestris candidate species 16 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD12 in Burriel-Carranza et al. 2024; see Table 1) [27, 28].

Paratypes.

IBES7257 (sample code S7257; MorphoBank M849924–M849928), adult female from Wadi As Sareen Nature Reserve, 1,683 m asl, Eastern Hajars (North Oman), 22.13167’N, 58.61889’E, WGS84, collected in May 2011 by S. Carranza, F. Amat and E. Gómez-Díaz (assigned to P. r. rupestris candidate species 16 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD12 in Burriel-Carranza et al. 2024; see Table 1) [27, 28]; MZB 2024–0989 (sample code CN192; MorphoBank M849930–M849932), juvenile from Wadi As Sareen Nature Reserve, 1,682 m asl, Eastern Hajars (North Oman), 22.13182’N, 58.61912’E, WGS84, collected in May 2014 by S. Carranza (assigned to P. r. rupestris candidate species 16 from Garcia-Porta et al. 2017 and to Pristurus rupestris BFD12 in Burriel-Carranza et al. 2024; see Table 1) [27, 28].

Other material examined.

So far, this new species is only known from three specimens (holotype ZFMK 104095 (sample code CN3704); paratypes: MZB 2024–0989 (sample code CN192) and IBES7257 (sample code S7257).

Diagnosis.

Pristurus assareen sp. nov. corresponds to a genetically highly distinct lineage from the Pristurus rupestris species complex sensu Garcia-Porta et al. (2017) [27] inhabiting a secluded and small region of the Eastern Hajar Mountains, North Oman. It is sister taxon to P. rupestris sensu stricto and constitutes the youngest divergence within the species complex about 3.7 mya (95% HPD: 3.0–4.5 mya; Fig 5). This small species of Pristurus is only known from a single locality and is characterized by a combination of the following characters: (1) a maximum recorded SVL of 23.96 mm; (2) 6–7 upper labial scales; (3) 3–4 lower labial scales; (4) 3–5 small postmental scales; (5) absence of mid-dorsal enlarged scales (crest) on the body; (6) laterally compressed tail usually with conspicuous dorsal and smaller ventral enlarged scales (crest) in males, and less conspicuous (sometimes absent) in females; (7) one unique mutation in alignment rag1: A instead of C in position 200; (8) one unique mutation in alignment rag2: A instead og G in position 325 (see S1 Appendix).

Etymology.

The species epithet ‘assareen’ is a noun in apposition that refers to the geographic distribution range of the species, so far only known from a single locality in Wadi As Sareen Nature Reserve, Eastern Hajar Mountains, Oman.

Morphological, genetic and phylogeographic remarks.

Pristurus assareen sp. nov. is morphologically cryptic from the other species of the Pristurus rupestris species complex. Although no diagnostic characters have been found, P. assareen sp. nov. tends to have a more robust body, similar to P. ali sp. nov., with relatively shorter brachia and wider scapular girdles than P. rupestris sensu stricto, P. omanensis sp. nov. and P. feulneri sp. nov.. This new species can be geographically separated from P. omanensis sp. nov., P. ali sp. nov. and P. feulneri sp. nov. by its distribution: P. assareen sp. nov. is restricted to a single locality in Wadi As Sareen Nature Reserve (Eastern Hajars), at an elevation of 1,680 m asl, where none of the aforementioned species co-occur. However, P. assareen sp. nov. is found syntopically with P. rupestris sensu stricto, thus the differentiation between these two species relies on molecular methods. Although there are only morphological data from two adult specimens in the multivariate analyses, it seems that P. assareen sp. nov. is morphologically more similar to P. ali sp. nov. than to any other Pristurus species within the species complex, sharing the ‘robust’ morphotype described in Garcia-Porta et al. (2017) [27] with the latter (Fig 3A and S2–S4 Tables).

All mitochondrial (Fig 4A), nuclear loci (Fig 4B), and genome-wide SNP analyses (Figs 3A, 3B, 5, S1 and S2) are fully concordant in the differentiation of P. assareen sp. nov. as a distinct species of its sister clade, P. rupestris sensu stricto. Pristurus assareen sp. nov. is monophyletic in both mitochondrial (Fig 4A) and nuclear phylogenetic analyses (Figs 5 and S1). In all phylogenetic reconstructions, it forms a clade together with P. rupestris sensu stricto representing the youngest split within the species complex, originating about 3.7 mya (Fig 5). The results of the nuclear networks for the cmos, mc1r, rag1 and rag2 loci shown in Fig 4B, indicate that P. assareen sp. nov. has some private alleles for each of these genes (not shared with any other species included in the present analysis). Although occurring in syntopy, no signs of admixture were detected between P. assareen sp. nov. and P. rupestris sensu stricto lineage 3 from Garcia-Porta et al. (2017) (P. rupestris BFD2 in Burriel-Carranza et al. 2024) [27, 28], and genetic and population genomic analyses show a great level of genetic differentiation between P. assareen sp. nov. and all other species described herein, including P. rupestris sensu stricto (uncorrected p-distance for 12S gene ranges from 10–23.7%; F_ST values range from 0.52–0.87; S5 and S6 Tables respectively). Additionally, although some intraspecific pairwise F_ST values within P. feulneri sp. nov. are similar to F_ST values between P. assareen sp. nov. and P. rupestris sensu stricto lineage 3 from Garcia-Porta et al. (2017) [27], when incorporating data on genetic distance (d_xy), P. assareen sp. nov. vs P. rupestris sensu stricto seems to be placed within the interspecific diversity cluster (colored dots in Fig 6). In addition, it is important to bear in mind that P. assareen sp. nov. and P. rupestris sensu stricto coexist syntopically at the only known locality for P. assareen sp. nov. in Wadi As Sareen Nature Reserve. In fact, P. rupestris sensu stricto seems much more abundant at this locality (S.C. pers. observ.).

Description of the holotype.

ZFMK 104095 (sample code CN3704) (Fig 22). Adult male. Incomplete specimen lacking the entire right hindlimb, parts of the cloacal fissure, and tail. Data on nine morphometric and two pholidotic variables (see Materials and Methods) are provided in S1 Table. SVL 22.3 mm (incomplete due to parts of the cloaca damaged), head length 30.3% of SVL, and head width 59% of head length. Moderately built, round body, habitus comparable to P. rupestris sensu stricto; limbs and tail not especially slender. Head robust and does not rise very steeply in profile, snout slightly blunt. Nostril separated from the rostral and situated between three scales: a wide supranasal extending to the midline margin, a small upper postnasal and a large lower postnasal extending laterally along the lower edge. Supranasals are separated in two scales. Scales on snout granular, polygonal and slightly pointed upwards. About eight scales in a straight line from the lower postnasal to the anterior edge of the orbit. Scales on snout, anterior to eyes, are larger than those on top of head. Around 20 scales across mid-orbital region. Palpebral fold edged anteriorly with large scales and not edged with pointed (ciliate) scales. Ear opening rounded. Upper labials (right/left) 7/7. Lower labials (right/left) 4/4, the fourth decreasing in size from the three large anterior scales. Four enlarged scales running backwards along the proximal borders of the third lower labials to end at about the level of the angle of the mouth. Mental large, rounded, truncated posteriorly by six gular scales. Gulars small, rather pointed posteriorly, becoming slightly imbricate on throat. Dorsal scales on body small, polygonal and homogeneous, slightly pointed posteriorly. Ventrals flat and distinctly imbricate. Scales on dorsal and anterior surface of the forelimbs slightly larger than dorsal body scales, flat and imbricate, fairly pointed. Scales beneath the upper forelimbs granular and smaller than ventral body scales; those beneath lower forelimbs large, flat, imbricate and polygonal, larger than ventral body scales. Claws relatively shallow and weakly recurved. Scales on dorsal and anterior surface of hindlimbs large, flat and imbricate, fairly pointed. Scales beneath the upper hindlimbs granular and smaller than ventral body scales, those beneath lower hindlimbs large, flat, imbricate and polygonal, larger than ventral body scales. Tail absent.

Coloration in alcohol grayish dorsally; blurred dorsal midline dark grayish. Dorsally and both left and right of the midline irregularly shaped reddish blotches present, surrounded by local grayish patterns slightly darker than the background coloration. Dorsolaterally thin pale reddish lines that dissolve into discontinuous lines posteriorly, and also ventrolaterally to the flanks up to spots comprised by individually colored scales. Blurred whitish spots distributed along the flanks. Head is the same color as the body with a broad dark brownish stripe running from the nostril through the eye and then dorsolaterally until above the ear opening. Single large dark blotches are located from beneath the angle of the mouth to the entire gular region reaching posteriorly to the insertion of the forelimbs. Most of them being large and prominent blotches on the throat becoming more blurred posteriorly. Ventral background coloration creamish-whitish. Limbs dark pale ventrally and brownish with blurred whitish spots dorsally, toes not banded.

The figured μ-CT-scanned specimen (Fig 22B) has a maximal skull length of 7.3 mm, maximal height of 3.0 mm and maximal width of 4.7 mm. 23 presacral vertebrae (vertebral column incomplete). Noteworthy minor qualitative cranial osteological differences (Fig 22C) to the other holotype specimens of the Pristurus rupestris species complex are: Vomer posteriorly only slightly rounded and bordered by a hoof-shaped opening; osseous naris edge smooth and slightly rounded; both dentaries fractured; premaxilla and nasal moderately steep to frontal region.

Variation.

Data on nine morphometric and two pholidotic variables (see Materials and Methods) for the two paratypes (see above) are provided in S1 Table. As of today, only three specimens of P. assareen sp. nov. have been found: one male, one female and one juvenile specimen. Therefore, knowledge on the variation of this species is limited to the material available. Both paratypes have broken or missing tails. Paratype IBES7257 (sample code S7257) has the throat sliced. Dorsal coloration similar for both paratypes, with conspicuous dorsal midline (especially in the female specimen), colored pale-beige. Background coloration is grayish-brownish with reddish spots distributed in longitudinal lines separated by dorsal bright spots. Multiple gular blotches present in both specimens. Ventral pattern uniform pale beige-whitish, with reddish spots distributed ventrolaterally only (Fig 23).

Distribution.

Pristurus assareen sp. nov. is only known from a single locality in the Wadi As Sareen Nature Reserve, Eastern Hajars, North Oman (Figs 24 and 25). Despite extensive surveys across surrounding wadis and the whole Hajar Mountain range, this secluded taxon has never been found anywhere else (Fig 25). It occurs at 1,680 m asl and is completely sympatric and syntopic with P. rupestris sensu stricto and more specifically with lineage 3 sensu Garcia-Porta et al. (2017) [27]. Therefore, this new species is endemic to Oman and, so far, constitutes the species of vertebrate with the smallest distribution range in Arabia.

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Fig 25.

Distribution of P. assareen sp. nov. in Arabia including (A) the single locality this species is known from within the Hajar Mountains range context; (B) a close-up of the Wadi As Sareen where the species is endemic to.

https://doi.org/10.1371/journal.pone.0315000.g025

Habits.

Very little data exists on this very secretive species of the Pristurus rupestris species complex. The only three known specimens were found during the day and at sunset in a rocky plateau in complete syntopy with Pristurus rupestris sensu stricto (Fig 24). During one of the expeditions to the Hajar Mountains carried out to study the Pristurus rupestris species complex, only two specimens out of a total of 25 specimens collected at the only known locality of Pristurus assareen sp. nov. at Wadi As Sareen Nature Reserve belonged to this species, while the remaining 23 specimens belonged to Pristurus rupestris sensu stricto (lineage 3 sensu Garcia-Porta et al. 2017) [27].

Conservation.

This species is currently considered to be endemic to Wadi As Sareen Nature Reserve in the Eastern Hajar Mountains, Oman. It occurs in a single locality with an area of occupancy (AOO) of 4 km², and is considered to occur in one location based on the inferred threat from competition with a lowland lineage of Pristurus rupestris sensu stricto (lineage 3 from Garcia-Porta et al. 2017) [27]. The species should be assessed as Critically Endangered (CR B2ab(ii,v)) on the basis of restricted AOO, and continuing decline in the AOO and in the number of mature individuals.